Your Ad HereFresno County is a county located in the U.S. state of California. As of 2016, it had an estimated population of 979,915. The county seat is Fresno.HistoryFresno County was formed in 1856. The county is named after Fresno Creek. Fresno in Spanish signifies "ash tree" and it was due to the abundance of mountain ash or ash trees in the county that it received its name.